Internally-lighted or back-lit signs typically have a housing with one or more electric lighting fixtures for supporting and energizing gas-discharge electric lamps' (such as neon or fluorescent tube lamps), and associated electrical wiring to conduct electricity from the lighting fixtures to a power source. At least one side of the housing supports a display sheet (such as a rigid, semi-rigid, or flexible sheet made of cloth, paper, glass, polymer, or the like) that is at least partially translucent, the sheet including lettering, symbols, artwork, or the like. Light from the lamps inside the housing projects through the display sheet to illuminate the lettering or artwork on the sheet, for example.